Speed-control system



Dec. 11, 1923. 1,476,997

' w. N. MOTTER SPEED CONTROL SYSTEM Filed Nov. 5, 1919 2 Sheets-Sheet 1 Dec. 11, 1923. 1,476,997

7 w. N. MOTTER SPEED CONTROL SYSTEM Filed Nov. 5, 1919 2 Sheets-Sheet 2 Patented Dec. 11, 1923.

MANUFACTURING COMPANY, OF MILWAUKEE,

DELAWARE.

SPEED-CONTROL SYSTEM.

, L Application filed November To all whom it may concern.

Be it known that l/VILLIAM N. MorrER, a citizen of the United States of America, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, has invented a certain new and useful Improvement in Speed-Control Systems, of which the following is a specification.

This invention relates to speed controlling systems and is particularly useful for controlling two or more motors which motors may be applied to do the work of driving the rolls of a steel mill, paper mill, sugar mill, etc.

It frequently occurs in connection with machinery driven by a plurality of motors, especially where the machinery acts upon a continuous piece of material, that it is desirable to keep the speed ratios of all of the motors constant so that, for example, the material will not be stretched, or sag or be buckled between the various elements of the machinery. Accordingly, one of the objects of the invention is the provision of a system whereby the ratio of the speeds of two motors may be kept substantially constant, even though the speed of one of the motors may vary.v

Another object of the. invention is the provision of a system whereby the ratios of the speeds of a plurality of motors may be "kept substantially constant, even though the speed of one of the motors may vary.

Another object of the invention is the provision of a system for accomplishing the above named results in a positive and direct manner, and whereby the predetermined speed ratios of the motors may be varied by mechanical means. Other objects will appear hereinafter as the description of the invention proceeds.

The novel features of the invention will appear from this specification and the drawings which form a part thereof and show three embodiments of the invention, and all these novel features are intended .to be pointed out in the claims.

In' the drawings Fig. 1 shows the invention, in diagrammatic form, as it may be applied to the regulation of the speeds of two motors.

Fig. 2 shows the invention, ,in diagrammatic form, as it may be applied in and a, 1919. Serial No. 335,963.

extended to the regulation of the speeds of more than two motors.

Fig. 3 is a modification of bodiment disclosed in Fig.

In Fig. 1, motors 8, 10, to be regulated, are shown fed from the suppl line 1. The motors are here shown as of t e direct current type, for purposes of illustration, and may be started by rheostats 4, 6 throu h the armature circuits thereof respective y, although any other starting means, or other sources of supply may be utilized.

The motor 10 is provided with an auX- iliary shaft 12 connected in any convenient manner to the main shaft of the motor. This auxiliary shaft may be of small size as it is not intended to transmit any substantial amount of power as will hereinafter more fully appear. A bevel pinion 24 is driven from the auxiliary shaft 12 through a pair of bevel gears 25, 26. The bevel pinion 24 meshes with a bevel gear 21 associated with the housing20 of a differential gear. With said housing are also associated the planetary cars 22, 23 constituting one (element or gear. The planetary gears cooperate with the bevel gears 36, '37 comprising the other two elements ofthe differential gear. The bevel gear 37 is driven by a shaft 17 which in turn is driven by an auxiliary shaft 11 associated with the main shaft of the motor 8. Between the-shafts 17 and 11 is inter posed a speed changing mechanism 540. This speed changing mechanism may be of any suitable form but is preferably one utilizing only mechanical force as is implied by the term mechanism. The speed changing mechanism here shown comprises two double conical pulleys 13, 15, the two frustoconical portions of each pulley being movable toward and away from each other. Mechanism may be provided for moving the parts of one pulley toward each other while moving the parts of another pulley away from each other, operated by the shaft 16, the effect being to vary the relative diameters of the effective driving portions of the pulleys cooperating with the belt 14. Turning of the adjusting'shaft 16 in one direction or the-other thus causes a variation in the speed ratios of the shafts 11, 17. The mechanism 540 may, if desired, be inthe type of em- 2.

the differential lated gear 31 driven by associated with a shaft terposed between the other motor and the differential as shown, for example, in Ti .2.

The motor 10 is provided with a old winding 9 supplied from the exciter bus 35 through'leads 19 and a rheostat 30. The field 7 of the motor 8 is also supplied from the exciter bus '35 through leads 18, an adjusting rheostat 27 and a regulating rheostat 32 being connected in series. "1"

The movable member 34 of the regulating rheostat is mounted to move with a mutia gear or pinion 29 28. The shaft 28 may be driven from one of the elements of the differential gear, the bevel gear 36.

The motors 8, 10 are here shown as driving the rolls3, 5 of a steel mill, although their application is, of course, not limited to this use.

A circuit breaker 2 may be provided in the main lines of supply to stop the motors in case of overload.

The operation of Fig. 1 is as follows:

Assuming that the motors 8, 10 are operating at normal speed the material passing through the rolls 5 goes to the rolls 3 and it is clear that in order to prevent'the material between'these rolls from being either stretched or buckled the speed of the motor 8 must not remain constant if the speed of motor 10 varies, but the ratio of the speeds of the two motors must remain the same. If the motors are operating at their proper speeds the shafts 12, 17 will rotate at such relative speeds as to result motion of'the bevel gear'36 of'the differential and thus the arm 34 of rheostat 32 will remain stationary. If, however, the speed of motor 10 varies there will be a resultant motion of the bevel gear 36 and will be moved so as to either increase or dethe system disclosed in crease the speed of motor 8- as the case may be. A similar action will clearly take place if the speed of motor 8 is varied, as for example, by the addition or removal of load, any variation being immediately reflected in themovable arm 34 of the regulating rheostat, thereby keeping the speed of motor 8 at its initial Value, assuming that there has been no change in the speed of motor 10.

The predetermi d speed ratio which is kept constant by the System hereinbefore described may be set a d changed by the speed changing mechanism motors 8, 10 to be operated at a given speed ratio and that the adjusting shaft 16 of the speed changing mechanism is operated to cause the ratio of the speed of theshaft 11, to that of shaft 17 to become larger, the bevel gear 37 will at first be driven at a speed which will cause motion of the bevel gear 36 and consequently of the movable arm 34. The ,movable arm 34 will act to reguspect to the be so high in the instance shown,

in no.

the arm 34 540. Assuming the agents? late the resistance of the field 7 of the nine tor 8 to such an extent that the speed of said motor and consequently shaft 17 with respeed of the shaft 12 willbe again of such a value that no motion of the bevel gear 36 will result. It is clear that to accomplish this the speed of motor 8 with respect to as before adjustment ofthe shaft 16 was made, because of the higher speed ratio between shafts'll, 17. The newly predetermined speed ratio, vwill then be kept constant by the diflerential speed regulating system in the manner, already described.

Adjustme t of the regulating performance ofthe rheostat 32 may be secured by the adjusting rheostat 27. The speed of motor 10 may be varied by rheostat 30.

If at any time there is a wide difference between the speeds of motors 8, 10 it is desirable that there be some form of interruptible connection between the regulating rheostat arm 34 and the bevel gear 36 to prevent overtravel and continuous rotation of the said arm. This is provided for by the mutilated pinion 3,1.

A centering spring 33 is provided which biases the arm 34 to a substantially central position whether the arm be moved clockwise or counterclockwise. Assuming that gear 29 has rotated direction and rotated gear 31, against the bias of spring 33, in a clockwise direction to the left hand limit of the control range of arm 34, the driving connection will clearly be interrupted and further rotation of gear 29 in the same direction will have no effect on gear 31. If, now,the direction of rotation of gear 29 be reversed, the driving connection will obviously be re-established automatically due to the biasing action of spring 33.

One of theways in which the invention may be applied in and extended to the reg ulation of more than two motors is shown in Fig. 2 in which each motor is controlled from the next preceding motor. All of the motors 45, 46, 47 may rheostat 38, 40, 42 being provided. Motor 47 is provided with an auxiliary shaft 53 driving one element of the differential 69 through thespeed changing mechanism 56 (which is here indicated as similar to mechanism 540 in Fig. 1) and the bevel gears 62, 63. The next motor 46 drives another element of the differential 69, through an auxiliary shaft 52 and a bevel pinion 65. The third element of the difierential controls the regulating rheostat 68 which is in series with the field winding 49 of motor 46.

From the auxiliary shaft 52 ofmotor 46 is also driven a pair of bevel gears 60, 61, transmitting motion changing mechanism 55' to one element of.

the speed of motor 10 need not through the speed in a counterclockwise another differential gear 67. A second element of said differential is driven through the bevel pinion 64 by the auxiliary shaft 51 associated with the next motor 45. The third element of the differential 67 controls the movable arm of the regulating rheostat 66, in series with the field winding 48 of motor 45. v If there are more than three motors the auxiliary shaft 51 may in like manner drive a mechanism 54 of the next motor, and so on.

The speed of motor 47 by the field rheostat 72.

Adjusting rheostats 70, 71 may be provided in the field windings of motors 45, 46 as already noted in connection with Fig. 1, and all of the field windings may be supplied from the exciter bus 73.

The operation of the system disclosed in Fig. 2 is as follows:

While the motors are running at their normal speed ratios the speeds are such that may be controlled the two elements of the differential 69,

driven respectively by motors 46, 47, and the two elements of differential 67, driven respectively by motors 45, 46, rotate at speeds such that there will be no resultant motion of the arms of the regulating rhe'ostats 66, 68. Should, however, the speed" of motor 47 change either by reason of a variation of load or by reason of direct speed control through the rheostat 72, the

:. arm of the regulating rheostat 68 will move In such a direction that the speed of motor 46 will follow that of motor 47 and in such proportion that the speed ratio of the two will remain the same. As a result of the fact that motor 46 also elements of the differential 67 associated with motor the change in speed of motor 46 will cause such a resultant motion of the arm of the regulating rheostat 66 that the speed of. motor 45 will follow that of motor 46, and in such proportion that the speed ratio will remain at its initial value. It will thus be seen that the speed ratios of the entire set will remain the same.

Motors 45, 46, 47, are shown 'as each driving rolls or other work devices 39, 41, 43, but this is notessen ial as, for example, motor 47 may be a sxgiall motor running light except. for the sm 11 load imposed by the differential speed 00 trolling means.

The system disclosed in Fig. 3 differs from that in Fig. 2 in that each motor is controlled from what may be termed the first motor 1 or master motor directly and not from the next preceding motor.

by causing the master by the starting means 79 and fed from the supply line 74, to drive an auxiliary shaft and, in turn, a line shaft which may comprise parts 101, 102, 103 through This is accomplished motor 86 controlled pair of bevel gears 58, 59 to a speed. changing drives one of the the bevel gears 104. A differential gear'100 is driven on the one hand through the bevel pinion 92 and the auxiliary shaft 89 associated with the next motor 84, and on the other hand from the line shaft 103 through the speed changing mechanism 98. The third element of said differential controls the regulating rheostat 94 in series with the field 85 of the motor 84. Another differential 99 is in like manner controlled from the inotor 82 and from the shaft 102 through the speed changing mechanism 96. The third element of said differential controls the regulating rheostat 93, in series with the field winding 83 of motor 82. If

there are more than three motors the next succeeding motor will be controlled from a speed changing mechanism 109, and so on. The master motor 86 may have its speed controlled by its field winding 87 and the rheostat 107, and all of the field win-dings of the motors may be fed from the exciter bus 108, and as in the previous instance, adjusting rheostats 105, 106 may be provided.

The motors in driving rolls 76, 78, 80 respectively, but as stated in connection with Fig. 2 it is not essential that the master motor 86 drive any work device.

The operation of the system disclosed in Fig. 3 will be clear without any further description.

It should be understood that it is not desired to limit the invention claimed to the exact details of construction herein Fig. 3 are indicated as shown and described, for obvious modificacontrolling one of said motors, said c0ntrolling means havin a definite control range, and means provi ing for the condition of abnormal difference in speed between said -motors including an interruptible driving1 connection between said controlling means and said differential means, whereby said differential means cannot move said controlling means out of its control range, and whereby a differential movement of said differential means corresponding to motion of said controlling means into said control range causes reestablishment of said driving connection.

2. In combination, two motors, means for maintaining the relative speed of said motors substantially constant including differential means having elements which are adapted to be continuously responsive to the speeds means whereby said difl'erentia} difierence in speed between said motors including an interruptible driving connection between said rheostat and said diderential not move said rheostat onto its control range and whereby a difierential movement of said difi'erential means corresponding to motion of said rheostat into said control range causes reestablishment of said driving connection.

3. lln combination, two motors, means for maintaining the relative speed of said motors constantincluding differential means having elements which are adapted to be continuously responsive to the speeds of said motors, means controlled by differential movement of said differential means for controlling one of said motors, said controlling means having a definite control range, and means providing for the condition of abnormal dif ferenoe in speed between said motors including an interruptible driving connection between said controlling means and said differential means, said interruptible driving connection including a mutilated gear associated with said controlling means and a v the inventor is afiixed hereto.

gear driving said mutilated gear associated with said differential means whereby said diilerentlal means cannot move said controlmeans canintone? ling means out of its control range and. whereby a difl'erential movement of said difi'erential means corresponding to motion of said controlling means into said control range causes reestablishment of said driving connection.

a. lln combination, two motors, means for maintaining the normal relative speed of said motors substantially constant including diflerential means havingelements which are adapted to be continuously responsive to the speed of said motors, means controlled by diflerential movement of said differential means for controlling one of said motors, said controlling means having a definite control range, and means providing for the condition of continued differential movement resulting from a continued abnormal relative speed including interruptible means between said controlling means and said differential means whereby when said difierential means has moved said controlling means to a. limit or its control range" said differential means may continue its movement without atlect on said controlling means, and a spring included in said interruptible driving means for causing re-establishment of the driving connection when said differential movement corresponds to motion of said controlling means into said control range.

lln testimony whereof, the signature of wrnnrmn N. MOTTER. 

